/*

 * rdbmp.c

 *

 * Copyright (C) 1994-1995, Thomas G. Lane.

 * This file is part of the Independent JPEG Group's software.

 * For conditions of distribution and use, see the accompanying README file.

 *

 * This file contains routines to read input images in Microsoft "BMP"

 * format (MS Windows 3.x, OS/2 1.x, and OS/2 2.x flavors).

 * Currently, only 8-bit and 24-bit images are supported, not 1-bit or

 * 4-bit (feeding such low-depth images into JPEG would be silly anyway).

 * Also, we don't support RLE-compressed files.

 *

 * These routines may need modification for non-Unix environments or

 * specialized applications.  As they stand, they assume input from

 * an ordinary stdio stream.  They further assume that reading begins

 * at the start of the file; start_input may need work if the

 * user interface has already read some data (e.g., to determine that

 * the file is indeed BMP format).

 *

 * This code contributed by James Arthur Boucher.

 */



#include "cdjpeg.h"		/* Common decls for cjpeg/djpeg applications */



#ifdef BMP_SUPPORTED





/* Macros to deal with unsigned chars as efficiently as compiler allows */



#ifdef HAVE_UNSIGNED_CHAR

typedef unsigned char U_CHAR;

#define UCH(x)	((int) (x))

#else /* !HAVE_UNSIGNED_CHAR */

#ifdef CHAR_IS_UNSIGNED

typedef char U_CHAR;

#define UCH(x)	((int) (x))

#else

typedef char U_CHAR;

#define UCH(x)	((int) (x) & 0xFF)

#endif

#endif /* HAVE_UNSIGNED_CHAR */





#define	ReadOK(file,buffer,len)	(JFREAD(file,buffer,len) == ((size_t) (len)))





/* Private version of data source object */



typedef struct _bmp_source_struct * bmp_source_ptr;



typedef struct _bmp_source_struct {

  struct cjpeg_source_struct pub; /* public fields */



  j_compress_ptr cinfo;		/* back link saves passing separate parm */



  JSAMPARRAY colormap;		/* BMP colormap (converted to my format) */



  jvirt_sarray_ptr whole_image;	/* Needed to reverse row order */

  JDIMENSION source_row;	/* Current source row number */

  JDIMENSION row_width;		/* Physical width of scanlines in file */



  int bits_per_pixel;		/* remembers 8- or 24-bit format */

} bmp_source_struct;





LOCAL int

read_byte (bmp_source_ptr sinfo)

/* Read next byte from BMP file */

{

  register FILE *infile = sinfo->pub.input_file;

  register int c;



  if ((c = getc(infile)) == EOF)

    ERREXIT(sinfo->cinfo, JERR_INPUT_EOF);

  return c;

}





LOCAL void

read_colormap (bmp_source_ptr sinfo, int cmaplen, int mapentrysize)

/* Read the colormap from a BMP file */

{

  int i;



  switch (mapentrysize) {

  case 3:

    /* BGR format (occurs in OS/2 files) */

    for (i = 0; i < cmaplen; i++) {

      sinfo->colormap[2][i] = (JSAMPLE) read_byte(sinfo);

      sinfo->colormap[1][i] = (JSAMPLE) read_byte(sinfo);

      sinfo->colormap[0][i] = (JSAMPLE) read_byte(sinfo);

    }

    break;

  case 4:

    /* BGR0 format (occurs in MS Windows files) */

    for (i = 0; i < cmaplen; i++) {

      sinfo->colormap[2][i] = (JSAMPLE) read_byte(sinfo);

      sinfo->colormap[1][i] = (JSAMPLE) read_byte(sinfo);

      sinfo->colormap[0][i] = (JSAMPLE) read_byte(sinfo);

      (void) read_byte(sinfo);

    }

    break;

  default:

    ERREXIT(sinfo->cinfo, JERR_BMP_BADCMAP);

    break;

  }

}





/*

 * Read one row of pixels.

 * The image has been read into the whole_image array, but is otherwise

 * unprocessed.  We must read it out in top-to-bottom row order, and if

 * it is an 8-bit image, we must expand colormapped pixels to 24bit format.

 */



METHODDEF JDIMENSION

get_8bit_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)

/* This version is for reading 8-bit colormap indexes */

{

  bmp_source_ptr source = (bmp_source_ptr) sinfo;

  register JSAMPARRAY colormap = source->colormap;

  JSAMPARRAY image_ptr;

  register int t;

  register JSAMPROW inptr, outptr;

  register JDIMENSION col;



  /* Fetch next row from virtual array */

  source->source_row--;

  image_ptr = (*cinfo->mem->access_virt_sarray)

    ((j_common_ptr) cinfo, source->whole_image,

     source->source_row, (JDIMENSION) 1, FALSE);



  /* Expand the colormap indexes to real data */

  inptr = image_ptr[0];

  outptr = source->pub.buffer[0];

  for (col = cinfo->image_width; col > 0; col--) {

    t = GETJSAMPLE(*inptr++);

    *outptr++ = colormap[0][t];	/* can omit GETJSAMPLE() safely */

    *outptr++ = colormap[1][t];

    *outptr++ = colormap[2][t];

  }



  return 1;

}





METHODDEF JDIMENSION

get_24bit_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)

/* This version is for reading 24-bit pixels */

{

  bmp_source_ptr source = (bmp_source_ptr) sinfo;

  JSAMPARRAY image_ptr;

  register JSAMPROW inptr, outptr;

  register JDIMENSION col;



  /* Fetch next row from virtual array */

  source->source_row--;

  image_ptr = (*cinfo->mem->access_virt_sarray)

    ((j_common_ptr) cinfo, source->whole_image,

     source->source_row, (JDIMENSION) 1, FALSE);



  /* Transfer data.  Note source values are in BGR order

   * (even though Microsoft's own documents say the opposite).

   */

  inptr = image_ptr[0];

  outptr = source->pub.buffer[0];

  for (col = cinfo->image_width; col > 0; col--) {

    outptr[2] = *inptr++;	/* can omit GETJSAMPLE() safely */

    outptr[1] = *inptr++;

    outptr[0] = *inptr++;

    outptr += 3;

  }



  return 1;

}





/*

 * This method loads the image into whole_image during the first call on

 * get_pixel_rows.  The get_pixel_rows pointer is then adjusted to call

 * get_8bit_row or get_24bit_row on subsequent calls.

 */



METHODDEF JDIMENSION

preload_image (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)

{

  bmp_source_ptr source = (bmp_source_ptr) sinfo;

  register FILE *infile = source->pub.input_file;

  register int c;

  register JSAMPROW out_ptr;

  JSAMPARRAY image_ptr;

  JDIMENSION row, col;

  cd_progress_ptr progress = (cd_progress_ptr) cinfo->progress;



  /* Read the data into a virtual array in input-file row order. */

  for (row = 0; row < cinfo->image_height; row++) {

    if (progress != NULL) {

      progress->pub.pass_counter = (long) row;

      progress->pub.pass_limit = (long) cinfo->image_height;

      (*progress->pub.progress_monitor) ((j_common_ptr) cinfo);

    }

    image_ptr = (*cinfo->mem->access_virt_sarray)

      ((j_common_ptr) cinfo, source->whole_image,

       row, (JDIMENSION) 1, TRUE);

    out_ptr = image_ptr[0];

    for (col = source->row_width; col > 0; col--) {

      /* inline copy of read_byte() for speed */

      if ((c = getc(infile)) == EOF)

	ERREXIT(cinfo, JERR_INPUT_EOF);

      *out_ptr++ = (JSAMPLE) c;

    }

  }

  if (progress != NULL)

    progress->completed_extra_passes++;



  /* Set up to read from the virtual array in top-to-bottom order */

  switch (source->bits_per_pixel) {

  case 8:

    source->pub.get_pixel_rows = get_8bit_row;

    break;

  case 24:

    source->pub.get_pixel_rows = get_24bit_row;

    break;

  default:

    ERREXIT(cinfo, JERR_BMP_BADDEPTH);

  }

  source->source_row = cinfo->image_height;



  /* And read the first row */

  return (*source->pub.get_pixel_rows) (cinfo, sinfo);

}





/*

 * Read the file header; return image size and component count.

 */



METHODDEF void

start_input_bmp (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)

{

  bmp_source_ptr source = (bmp_source_ptr) sinfo;

  U_CHAR bmpfileheader[14];

  U_CHAR bmpinfoheader[64];

#define GET_2B(array,offset)  ((unsigned int) UCH(array[offset]) + \

			       (((unsigned int) UCH(array[offset+1])) << 8))

#define GET_4B(array,offset)  ((INT32) UCH(array[offset]) + \

			       (((INT32) UCH(array[offset+1])) << 8) + \

			       (((INT32) UCH(array[offset+2])) << 16) + \

			       (((INT32) UCH(array[offset+3])) << 24))

  INT32 bfOffBits;

  INT32 headerSize;

  INT32 biWidth = 0;		/* initialize to avoid compiler warning */

  INT32 biHeight = 0;

  unsigned int biPlanes;

  INT32 biCompression;

  INT32 biXPelsPerMeter,biYPelsPerMeter;

  INT32 biClrUsed = 0;

  int mapentrysize = 0;		/* 0 indicates no colormap */

  INT32 bPad;

  JDIMENSION row_width;



  /* Read and verify the bitmap file header */

  if (! ReadOK(source->pub.input_file, bmpfileheader, 14))

    ERREXIT(cinfo, JERR_INPUT_EOF);

  if (GET_2B(bmpfileheader,0) != 0x4D42) /* 'BM' */

    ERREXIT(cinfo, JERR_BMP_NOT);

  bfOffBits = (INT32) GET_4B(bmpfileheader,10);

  /* We ignore the remaining fileheader fields */



  /* The infoheader might be 12 bytes (OS/2 1.x), 40 bytes (Windows),

   * or 64 bytes (OS/2 2.x).  Check the first 4 bytes to find out which.

   */

  if (! ReadOK(source->pub.input_file, bmpinfoheader, 4))

    ERREXIT(cinfo, JERR_INPUT_EOF);

  headerSize = (INT32) GET_4B(bmpinfoheader,0);

  if (headerSize < 12 || headerSize > 64)

    ERREXIT(cinfo, JERR_BMP_BADHEADER);

  if (! ReadOK(source->pub.input_file, bmpinfoheader+4, headerSize-4))

    ERREXIT(cinfo, JERR_INPUT_EOF);



  switch ((int) headerSize) {

  case 12:

    /* Decode OS/2 1.x header (Microsoft calls this a BITMAPCOREHEADER) */

    biWidth = (INT32) GET_2B(bmpinfoheader,4);

    biHeight = (INT32) GET_2B(bmpinfoheader,6);

    biPlanes = GET_2B(bmpinfoheader,8);

    source->bits_per_pixel = (int) GET_2B(bmpinfoheader,10);



    switch (source->bits_per_pixel) {

    case 8:			/* colormapped image */

      mapentrysize = 3;		/* OS/2 uses RGBTRIPLE colormap */

      TRACEMS2(cinfo, 1, JTRC_BMP_OS2_MAPPED, (int) biWidth, (int) biHeight);

      break;

    case 24:			/* RGB image */

      TRACEMS2(cinfo, 1, JTRC_BMP_OS2, (int) biWidth, (int) biHeight);

      break;

    default:

      ERREXIT(cinfo, JERR_BMP_BADDEPTH);

      break;

    }

    if (biPlanes != 1)

      ERREXIT(cinfo, JERR_BMP_BADPLANES);

    break;

  case 40:

  case 64:

    /* Decode Windows 3.x header (Microsoft calls this a BITMAPINFOHEADER) */

    /* or OS/2 2.x header, which has additional fields that we ignore */

    biWidth = GET_4B(bmpinfoheader,4);

    biHeight = GET_4B(bmpinfoheader,8);

    biPlanes = GET_2B(bmpinfoheader,12);

    source->bits_per_pixel = (int) GET_2B(bmpinfoheader,14);

    biCompression = GET_4B(bmpinfoheader,16);

    biXPelsPerMeter = GET_4B(bmpinfoheader,24);

    biYPelsPerMeter = GET_4B(bmpinfoheader,28);

    biClrUsed = GET_4B(bmpinfoheader,32);

    /* biSizeImage, biClrImportant fields are ignored */



    switch (source->bits_per_pixel) {

    case 8:			/* colormapped image */

      mapentrysize = 4;		/* Windows uses RGBQUAD colormap */

      TRACEMS2(cinfo, 1, JTRC_BMP_MAPPED, (int) biWidth, (int) biHeight);

      break;

    case 24:			/* RGB image */

      TRACEMS2(cinfo, 1, JTRC_BMP, (int) biWidth, (int) biHeight);

      break;

    default:

      ERREXIT(cinfo, JERR_BMP_BADDEPTH);

      break;

    }

    if (biPlanes != 1)

      ERREXIT(cinfo, JERR_BMP_BADPLANES);

    if (biCompression != 0)

      ERREXIT(cinfo, JERR_BMP_COMPRESSED);



    if (biXPelsPerMeter > 0 && biYPelsPerMeter > 0) {

      /* Set JFIF density parameters from the BMP data */

      cinfo->X_density = (UINT16) (biXPelsPerMeter/100); /* 100 cm per meter */

      cinfo->Y_density = (UINT16) (biYPelsPerMeter/100);

      cinfo->density_unit = 2;	/* dots/cm */

    }

    break;

  default:

    ERREXIT(cinfo, JERR_BMP_BADHEADER);

    break;

  }



  /* Compute distance to bitmap data --- will adjust for colormap below */

  bPad = bfOffBits - (headerSize + 14);



  /* Read the colormap, if any */

  if (mapentrysize > 0) {

    if (biClrUsed <= 0)

      biClrUsed = 256;		/* assume it's 256 */

    else if (biClrUsed > 256)

      ERREXIT(cinfo, JERR_BMP_BADCMAP);

    /* Allocate space to store the colormap */

    source->colormap = (*cinfo->mem->alloc_sarray)

      ((j_common_ptr) cinfo, JPOOL_IMAGE,

       (JDIMENSION) biClrUsed, (JDIMENSION) 3);

    /* and read it from the file */

    read_colormap(source, (int) biClrUsed, mapentrysize);

    /* account for size of colormap */

    bPad -= biClrUsed * mapentrysize;

  }



  /* Skip any remaining pad bytes */

  if (bPad < 0)			/* incorrect bfOffBits value? */

    ERREXIT(cinfo, JERR_BMP_BADHEADER);

  while (--bPad >= 0) {

    (void) read_byte(source);

  }



  /* Compute row width in file, including padding to 4-byte boundary */

  if (source->bits_per_pixel == 24)

    row_width = (JDIMENSION) (biWidth * 3);

  else

    row_width = (JDIMENSION) biWidth;

  while ((row_width & 3) != 0) row_width++;

  source->row_width = row_width;



  /* Allocate space for inversion array, prepare for preload pass */

  source->whole_image = (*cinfo->mem->request_virt_sarray)

    ((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,

     row_width, (JDIMENSION) biHeight, (JDIMENSION) 1);

  source->pub.get_pixel_rows = preload_image;

  if (cinfo->progress != NULL) {

    cd_progress_ptr progress = (cd_progress_ptr) cinfo->progress;

    progress->total_extra_passes++; /* count file input as separate pass */

  }



  /* Allocate one-row buffer for returned data */

  source->pub.buffer = (*cinfo->mem->alloc_sarray)

    ((j_common_ptr) cinfo, JPOOL_IMAGE,

     (JDIMENSION) (biWidth * 3), (JDIMENSION) 1);

  source->pub.buffer_height = 1;



  cinfo->in_color_space = JCS_RGB;

  cinfo->input_components = 3;

  cinfo->data_precision = 8;

  cinfo->image_width = (JDIMENSION) biWidth;

  cinfo->image_height = (JDIMENSION) biHeight;

}





/*

 * Finish up at the end of the file.

 */



METHODDEF void

finish_input_bmp (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)

{

  /* no work */

}





/*

 * The module selection routine for BMP format input.

 */



GLOBAL cjpeg_source_ptr

jinit_read_bmp (j_compress_ptr cinfo)

{

  bmp_source_ptr source;



  /* Create module interface object */

  source = (bmp_source_ptr)

      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,

				  SIZEOF(bmp_source_struct));

  source->cinfo = cinfo;	/* make back link for subroutines */

  /* Fill in method ptrs, except get_pixel_rows which start_input sets */

  source->pub.start_input = start_input_bmp;

  source->pub.finish_input = finish_input_bmp;



  return (cjpeg_source_ptr) source;

}



#endif /* BMP_SUPPORTED */

